3 Answers
3

As far as I know, the Ubuntu one server side software is proprietary, so that it is impossible to host your own Ubuntu One server. However there are several other techniques that can be employed in order to share your files across multiple computers. There is

sshfs: a filesystem which allows you to mount any remote file system you can access via SSH. So basically all you need on your server is an SSH server running and sshfs on your clients. sshfs mounts can be automatically mounted using the /etc/fstab file or using autofs.

nfs: the network file system is rather more complicated to deploy and (if not used correctly) has security issues. To my shame I have not looked into it deeply.

rsync: of course as bodhi.zazen suggests, you can always use rsync to "backup" your files. The problem with rsync is that unlike the Microsoft SyncToy out of the box it does not do two-way merging (and I am yet to find the option in rsync for that). Also unlike the two suggestions outlined above rsync does true synchronization as opposed to sharing one file system which is what the other two do. This has an upside: all changes are immediately shared between clients, and a downside: the mount is only available, when internet connectivity is available.

git: another option I may suggest to you, if you are manly working with text files is git. you can use it in a similar fashion as rsync but you gain the ability to roll back changes and better merge support (what happens, when two clients modify a file?). The downsides of this solution are a much higher disk space consumption (all of the incremental updates have to live somewhere) and a complicated user interface (as git is a source control tool, one has to create commits to share documents).